So David Moses Abraham etc were not saved did not get to heaven yet then?
No. none of them were saved. There is no salvation from the penalty of sin, which is the second death in the lake of fire, apart from Christ. OT believers in what God said to them are "JUSTIFIED" by their believing and their faith is imputed to them for righteousness. . This does not mean they all believed the same things but that they all believed God, what he said to them.
The gospel account is a case in point. Do you think the generation of Jesus Christ, when he came as the virgin born son of God, presented a different set of circumstances to be believed than the time before he came? How many people were required to believe that Jesus had come, in say, the days of Jeremiah and that he was the Messiah, the son of God?
Where is any consistent teaching in the OT that God is the father of Israel? Isn't it true that one of the purposes of the ministry of our Lord Jesus Christ was to reveal God as Father? Is this progressive revelation?
The revelation of God is a continuing drama of redemption that continues to unfold in history of time. Those of you who attempt to make prophecy a part of past history are doing the work of the enemy and are confusing the gospel.
In the NT we must believe that Christ died for our sins, was buried and rose again from the dead on the third day and no one will be justified by God who doesn't believe that.
Those OT justified believers, who had their faith imputed to them by God for righteousness, the Judge of all men, have had their sins washed away in the blood of the Lamb and they are certainly saved and are with the Father now but they were not delivered by hearing the gospel of Jesus Christ.
Romans 8 says this;
33 Who shall lay any thing to the charge of God's elect? It is God that justifieth.
Note: The elect here is determined by the context and the context of this discourse is the elect people of God, Israel, which begins in Rom 7:1 through Rom 11:12, where Paul shifts gears and outlines how this impacts the gentiles and how we should respond to these new revelations in the program of God.